1. Field of Invention
The present invention relates to a LCD (liquid crystal display) apparatus, and more particularly to a backlight assembly for accomplishing a high brightness and a direct illumination type LCD apparatus having the backlight assembly for improving a display quality.
2. Description of Related Art
Display apparatuses, such as LCD apparatuses, for visually interfacing the data processed by information processing devices have rapidly improved along with the development of the processing devices.
Since LCD apparatuses have a lighter weight and a more compact size than a CRT (Cathode Ray Tube) type display device, as well as full-color and high-solution functions, the LCD apparatuses have been widely used.
The LCD apparatuses convert variations in optical properties of a liquid crystal into variations in visual properties in order to display an image. The LCD apparatuses include a backlight assembly disposed under an LCD panel that supplies a light to the LCD panel to display the image.
Backlight assemblies include a direct illumination type backlight assembly and an edge illumination type backlight assembly in accordance with the position of a lamp installed therein. In the direct illumination type backlight assembly, a light generated from the lamp (which is disposed under an LCD panel) is directly illuminated onto the overall LCD panel. Thus, the direct illumination type backlight assembly may have a higher brightness than that of the edge illumination type backlight assembly, when several lamps are disposed on the LCD panel.
FIG. 1 is a schematic sectional view showing a conventional direct illumination type LCD apparatus.
Referring to FIG. 1, the direct illumination type LCD apparatus 100 includes an LCD panel assembly 110 for displaying an image and a backlight assembly 120 for supplying a light to the LCD panel assembly 110.
The backlight assembly 120 includes one or more lamps 121 for generating a first light, a reflection plate 122 for reflecting the first light and a diffusion plate 123 for diffusing the first light into a second light with a uniform brightness distribution. The lamps 121, reflection plate 122 and diffusion plate 123 are received in a receiving container.
The receiving container includes a bottom mold frame 124 and a bottom chassis 125. The bottom mold frame 124 is combined with the bottom chassis 125 by using hooks. The bottom mold frame 124 includes sidewalls on which the diffusion plate 123 is disposed. The bottom chassis 125 has a box shape wherein an upper face is opened to provide a receiving space having a predetermined depth. The reflection plate 122 is received in the receiving space and the lamps 121 are disposed on the reflection plate 122.
A portion of the first light is directly incident onto the diffusion plate 123 and another portion of the first light is incident onto the diffusion plate 123 after being reflected by the reflection plate 122. The first light is diffused through the diffusion plate 123, and the second light having an emitting angle wider than that of the first light is emitted from the diffusion plate 123.
The conventional direct illumination type LCD apparatus 100, however, has a non-uniform brightness distribution. That is, a first region “A” corresponding to a first illumination region of the lamps 121 has brightness relatively higher than that of a second region “B” corresponding to a second region between the lamps 121, as shown the brightness distribution curve 150 in FIG. 1. Thus, a display quality of the direct illumination type LCD apparatus 100 is deteriorated due to the non-uniform brightness distribution.
To solve the above-mentioned problem, another conventional direct illumination type LCD apparatus has been proposed as shown in FIG. 2.
FIG. 2 is a schematic sectional view showing a conventional direct illumination type LCD apparatus having a diffusion plate including light scattering patterns.
Referring to FIG. 2, a conventional direct illumination type LCD apparatus 160 includes a diffusion plate 123 under which light scattering patterns 123a are formed. The light scattering patterns 123a scatter the first light provided from the lamps 121. Particularly, the light scattering patterns 123a are positioned under the diffusion plate 123 corresponding to the first region “A”, so that the light scattering patterns 123a intercept the incident first light onto the first region “A”. The second light corresponding to the first region “A” is thus scattered by the scattering patterns and, accordingly, the brightness thereof is reduced. Hence, the brightness difference of the second light between the first and second regions “A” and “B” is reduced, so that the conventional direct illumination type LCD apparatus 160 generally may have a uniform brightness distribution.
However, the light scattering patterns 123a may be easily discolored by the ultraviolet rays emitted from the lamps 121 or the heat generated from the lamps 121 as time goes by. The discolored light scattering patterns 123a are directly projected onto a screen of the direct illumination type LCD apparatus 160, so the display quality of the direct illumination type LCD apparatus 160 may be deteriorated.
In addition, the brightness of the direct illumination type LCD apparatus 160 may be entirely decreased since the light scattering patterns 123a intercept the first light generated from the lamps 121.